The market for construction flashing and roofing products, including tab-type strip roofing shingles, window and door flashing and roofing underlayment, is very large. Each year, several million new homes are built in the United States and Canada utilizing roofing shingles, and additional millions of existing homes have their roofing materials replaced.
Commercial roofing products, other than very expensive slate, metal, tile, or cedar wood products used for very high end houses, are today either asphalt or fiberglass based. Asphalt and fiberglass products suffer from the disadvantages of the expense of raw materials, damage from the consequences of the use of highly combustible raw materials in their manufacture, surprisingly quick degradation when exposed to the elements and consequent short useful life, and in the South and Southeast, high levels of actual breakage caused by hail, have occurred.
Commercial waterproofing products today utilize hot-applied rubberized asphalt as a waterproofing membrane and protected roofing membrane. The hot-applied rubberized asphalt is typically produced with recycled content including crumb rubber. These systems require the use of a protection course which is typically modified asphalt reinforced with a scrim typically a fiberglass mat. These products also suffer from similar disadvantages which are the expense of raw materials, their combustible nature, high use temperatures during application, surprisingly quick degradation when exposed to the elements, and damage caused by hail. Typically these systems require the installation of additional ballast for protection. An addition disadvantage is that, at high temperatures, the asphalt portion can flow and creep leading to defects in the waterproofing or staining of the external areas of the structure.
Greenroofs are relatively new in the United States, but have been utilized throughout Europe for decades. One important component in the greenroof assembly is a root barrier to protect the asphaltic waterproofing membrane from damage caused by root penetration. The roots will seek nutrients from an organic-asphaltic waterproofing membrane. Therefore a non-asphaltic membrane must be utilized for the root barrier. Typically the membranes used for root barriers have been polyethylene sheets or PVC membranes. Depending upon the aggressiveness of the roots, the seams of the plastic components may be required to be sealed.
Sound control underlayments utilize a variety of products ranging from fused entangled elements, typically polymeric fibers, to 100% recycled crumb rubber. Due to the formulation, manufacturing process or performance properties, these membranes are typically very thick and costly.
The construction industry has therefore long sought a competitively priced, relatively low-cost, product that could be efficiently manufactured. Scientists and practical construction industry management have long searched for a product that used sustainable, higher quality raw materials than such traditional materials as asphalt and fiberglass.
The search for such new products has, up to now, also unsuccessfully looked at the potential for use of a major American waste product, which itself has not found commercial uses at anything approaching the volumes of waste materials produced. For almost as long as rubber tires have been manufactured, the question of finding an acceptable use for worn-out tires has stimulated invention. References to the history of this development are set forth in U.S. Pat. No. 4,851,500, where patents directed to recycling as old as 1957 are cited, with “related” patents as old as U.S. Pat. No. 1,550,968 (1925). Similarly, the concept of recycling rubber tire material by grinding such material into small pieces is quite old. U.S. Pat. No. 3,210,301 discloses two improvements for reducing the processing time of recycled rubber used for rubber compounding and describes the recycling use in 1965 as already “well known”. A 1978 U.S. Pat. No. 4,125,578 describes a heat process for reclaiming vulcanized “crumb rubber” from tires.
The use of large geometrical pieces of tires as roofing is similarly old. U.S. Pat. No. 3,803,792 for a “Tire Roof” discloses the construction of a roof covering made from cut and segmented waste tires, providing in effect a tile roof where the tiles are segments of tires. Work has continued in this unusual area of the use of cut-up tire segments up to the present day, with improvements in the configuration of the tire segments shown in U.S. Pat. Nos. 5,086,552 and 5,675,954 as recently as October, 1997. In none of these patents is any consideration shown of the possibility of the creation of a new roofing product from particles of tires and other materials. Similarly, there is no consideration shown of the utility of small (millimeter-sized) pieces of ground tire material.
The general concept of using small pieces of rubber, such as crumbs from the recycling process, to add desired characteristics to other materials is known. U.S. Pat. No. 4,109,041 (1978), as a representative example, teaches the use of waste rubber particles in making non-slip coatings on construction panels.
Several early patents are directed to the reuse of recycled tire waste to make various types of sheet goods, including roofing sheets. These early patents, and their more modern progeny, use heat and thermosetting agents to create molded articles. For example, U.S. Pat. No. 3,027,599 discloses a method of molding articles from scrap tire material, using a thermosetting binding agent. U.S. Pat. No. 3,267,187 discloses the use of crumb rubber (not specifically from scrap tires) in formed, resin-fused textured sheet flooring. U.S. Pat. No. 3,844,668 generally shows the use of recycled rubber from whole tires, reacted at high temperatures with asphalt, and then dissolved in kerosene or a similar hydrocarbon, to repair pavements or roofing.
Other patents teach the incorporation of utilizing rubber utilize crumb rubber to make rubber sheet goods or similar goods which might be used on roofs. One set of patents demonstrate attempts to obtain useful materials from rubber ingredients by essentially using pressure alone. U.S. Pat. No. 5,527,409 discloses a log-like structure created from pressed crumb rubber which is spirally sliced into sheets (with a separate waterproofing compound to be added after installation)—the patent does not disclose any elastomer or other blending additives and describes the only bonding mechanism as being pressure.
Another group of patents deals with batch-type molding or casting processes for making recycled rubber roofing products involving extensive curing (i.e., polymerization), in contradistinction to a continuous-type extrusion process followed by at most limited curing. U.S. Pat. No. 4,028,288 shows a heat and pressure-molded mixture of ground tires, including the fibrous tire cords, and a synthetic thermoplastic resin. The patent identifies a useful synthetic thermoplastic resin as comprising at least one of the materials polyethylene, styrene, and polypropylene.
U.S. Pat. No. 4,795,603 describes a process of mixing rubber waste and crushed polyethylene or polypropylene wastes together, and heating, pressing, and injecting them so as to mold them. The injection molding composition is described as useful for batch-type molding processes, rather than a continuous extrusion-type process.
U.S. Pat. No. 4,851,500, previously discussed, shows the use of scrap rubber, sulfur and pressure to make a cured rubber product for use as roofing products such as roll roofing, tiles, shakes and slates, and other materials. The patent describes this use as an improvement over prior art because it uses pressure rather than a working and plasticizing action such as in extrusion; it also requires the use of sulfur. Bertolino published European Patent Application 0 401 885 is similar, in that it emphasizes the admixture of waste rubbers, plastics, and fibers, mixed with polyethylene or another thermoplastic, and then heated by an extruder or any other similar system.
U.S. Pat. No. 5,254,405 and its continuation-in-part, U.S. Pat. No. 5,385,953, teach the embedding of crumb rubber in a polyurethane matrix. U.S. Pat. No. 5,258,222 utilizes crumb rubber in a cast, tile-like roofing product which is liquid, and cures after pouring. The patent teaches the requirement of epoxy resin or neoprene to hold the other materials together along with silica and other materials.
Three related patents (U.S. Pat. No. 5,453,313, its continuation U.S. Pat. No. 5,580,638, and its continuation-in-part U.S. Pat. No. 5,525,399) disclose the use of polysulfide together with rubber for structural strength. The continuation patents add fire retardant, ultraviolet protection compounds, and an asphalt matrix. The process which is common to all three patents requires the addition of polysulfide and extensive curing.
U.S. Pat. No. 5,635,551 discloses an improvement in the molding of articles using pulverized recycled tires by specifying a limited range of thermoplastic resins. The patent requires the use of five additional ingredients (starch, acetone, caustic soda, glass wool and ammonium phosphate) with starch, which must comprise at least 5% by weight of the finished composition, having the highest percentage requirement.
A number of alternate technologies for creating materials which gain their strength and hardness from covalent chemical bonds with crumb rubber have also been attempted.
U.S. Pat. No. 4,244,841 utilizes sulfur and zinc stearate as a cure mix to form a rolled product one inch in diameter suitable for roofing, and requires sulfur to achieve its result. U.S. Pat. No. 4,970,043 shows the use of a “cohesive base material” such as a styrene-butadiene block copolymer, and a minimum of “at least” 50% ground rubber. The patent also involves the recycling of exclusively high grade rubber.
U.S. Pat. No. 5,010,122 describes a thermoset composition comprising crumb rubber having a size less than 10 mesh, a thermoplastic material which can include olefinic polymers with blends of similar polymers, and one or more coupling agents. Covalent bonds are formed by reacting a coupling agent to both the crumb rubber and olefin polymers together. The patent describes the requirement of at least one coupling agent, and covalent bonds or equivalent chemical bridges between the rubber particle and the thermoplastic material. The patent specifically identifies silane coupling agents to form the required covalent bonds. The compositions and methods claimed in the instant invention do not contain a coupling agent.
The concept of a polyolefin sheet material for roofing, like that of a rubber material for roofing, is not new: see for example U.S. Pat. No. 5,256,228 ('228) and U.S. Pat. No. 3,547,674 describe the use of asphalt to anchor a polyolefin fabric, with more asphalt anchoring individual crumb rubber pellets attached to the fabric. The '228 patent requires a highly crystalline polyolefin to improve the weldability of the cured EPDM sheet so that overlapping sheet material layers can be heated sufficiently to bond adjacent sheets together. The inventive sheet product described herein does not require curing and is inherently weldable. The polyolefins utilized in the instant invention are homopolymers and have a crystallinity less than 25%, e.g., 2% to 25%.
There are a number of patents which utilize rubber plus an olefinic substance, but generally require specific chemicals appropriate to the particular polymerization reactions being described. See U.S. Pat. No. 4,311,628 which describes a blend of polyolefin resin and particles of EPDM rubber of a size below 50 microns average, cured using phenolic compounds. No phenolic curing agents are included in the compositions of the instant invention. U.S. Pat. No. 5,157,081 teaches a vulcanized rubber in a crystalline polyolefinic resin matrix. Rubbers useful are listed as bromobutyl rubber, chlorbutyl rubber, butyl rubber and mixtures thereof with curing required with a non-peroxide curing system. No curing agents (other than any contained in the vulcanized rubber) are included in the compositions of the instant invention. U.S. Pat. No. 5,290,886 adds low molecular weight ester plasticizers that are not included in the compositions of the instant invention.
U.S. Pat. No. 5,389,715 claims an uncured sheet of a polyolefin polymer roofing product which is made semi-self-sealing by curing in place on a rooftop through the inclusion of a “cure package.” U.S. Pat. No. 5,594,073 claims a roofing composition involving blends of two specific rubbers, a narrowly-defined urea composition, sulfur, an accelerator, and a cure activator. No urea compounds, cure accelerator or cure activator are included in the compositions of the instant invention.
A patent which teaches the use of rubber in roof shingles, U.S. Pat. No. 5,338,783, teaches the requirement of silicone rubber, silicon dioxide, and aggregates to make tab shingles. Silicon dioxide is not used in the compositions of the instant invention and the material is manufactured in continuous sheets that are cut to size.
There are a few patents which involve extrusion processes that combine crumb rubber and polyolefins. The first of these is U.S. Pat. No. 5,157,082. The patent shows a product made from 10-90 parts by weight of ground rubber, of a maximum 0.060 inches average size, and also describes about 90 to 10 parts by weight of polyolefin resin and at least 0.5 parts by weight of one or more functionalized olefin polymers per 100 parts by weight of polyolefin resin. A second product and process disclosed require about 90 to 10 parts by weight of one or more functionalized olefin polymers. Such functionalized olefin polymers are described to be a copolymer of at least one olefin and at least one ethylenically unsaturated organic monomer; wherein said organic monomer is selected from the group consisting of unsaturated mono or dicarboxylic acids having from 3 to 20 carbon atoms; acid anhydride, maleamic acid, acid halide, ester and metal salt derivatives of said unsaturated mono or discarboxylic acids; vinyl esters of saturated carboxylic acids, wherein the acid constituent of said saturated carboxylic acid has from 2 to 18 carbon atoms; vinyl alkyl ethers wherein said alkyl constituent has from 1 to 18 carbon atoms; vinyl halides; vinylidene halides; acrylonitrile; methacrylonitrile; and styrene. The extruded compositions useful herein do not contain said functionalized olefin polymers.
U.S. Pat. No. 5,523,328 discloses extrusion products employing crumb rubber and a polyolefin. The patent specifies that ground tire waste must comprise rubber and metal debris to provide 2×4 construction materials. The compositions useful herein do not include metal.
U.S. Pat. No. 6,194,519 requires a crumb rubber having a particle size in the range of 10-30 mesh (up to 0.066 inches). The ground vulcanized rubber useful herein has a maximum particle size of about 0.039 inches, preferably a maximum size of about 0.020 inches.